Furnace for heating hollow cylinders



June 9, 1925.

A. M D. DUCKHAM FURNACE FOR HEATING HOLLOW CYLINDERS Filed April 16, 1923 3 Sheets-Sheet 1 War/26% June 9, 1925.

A. M D. DUCKHAM FURNACE FOR HEATING HOLLOW CYLINDERS Filed April 16, 1923 3 Sheets-Sheet z June 9, 1925. 1,541,691

A. MCD. D'UCKHAM FURNACE FOR HEATING HOLLOW CYLINDERS Filed April 165, 1925 3 Sheets-Sheet 5 live Z72 Patented June 9, 1925.

ARTHUR MCDOUGALL DUCKHAM, OF LONDON, ENGLAND.

FURNACE FOR HEATING HOLLOW CYLINDERS.

Application filed. April 16, 1923. Serial No. 632,475.

To aZZ whom it may concern.

Be it known that I, ARTHUR MoDoUGAIL DUCKHAD'I, a subject ofthe King of Great Britain, residing in London, England, have invented certain new and useful Improvements in and Relating to Furnaces for Heating Hollow Cylinders, of which the following is a specification.

The heating of hollow cylinders ofv considerable diameter whether for their heattreatment, for enamelling' them or for any other purpose, presents difliculties both in respect of handling them and of heating them economically and uniformly.

According to this invention a' furnace for heating such cylinders is constructed as'an annular muifle furnace, the bottom of which is adapted to be lowered from the'furnace to receive the cylinder and to be raised again so as to introduce the cylinder into the annular muflle chamber. An advantage of. this form of chamber is that by construct ing it of radius suitably selected with ref-.

erence to the radius of the cylinder to be heated, the latter may be heated equally both internally and externally by the heated walls of the chamber.

The method of introducing objects into a furnace by placing them on a furnace bot tom capable of being raised and lowered, is known.

Its application according to this invention to an annular muflie furnace has the particular advantage that it permits the introduction and withdrawal of the cylinder with certainty that it will not come into contact with the walls of the annular chamber, operations difficult to perform if the cylinder is lowered into the chamber. I

The annular chamber is preferably surrounded by vertical flues so arranged that combustion occurs on the inner or outer side, or on both sides, of the annulus in fines which alternate with waste gas flues. For example, separate gas and air flues may be constructed radially above the chamber, gas from a producer or the like being admitted at the outer end of each gas flue and air, which has ascended preheating flues contiguone with waste gas flues, being admitted at the outer end of each air flue. Each pair of gas and air flues terminates in a vertical combustion flue on the inside of the annulus. The products of combustion descend these combustion flues and at the bottom pass into waste heat fines, of which there is one between each pair of air and gas flues. The products ascend the waste gas flues and pass through radial flues over the top of the chamber to descend corresponding vertical waste heat flues on the outside of the annulus, thereby serving to heat the aforesaid air preheating flues. The last-named waste heat flues deliver to a common chimney.

The annular chamber is preferably extended. somewhat below the brickwork setting by flanges of suitable annular plates so i that when. the movable bottom constructed as an annular trough, is in place, a scaling medium such as sand'or suitable liquid, may

close the chamber from access of air if desired. I

The bottom is conveniently supported on four rams capable of being raised and lowered hydraulically or otherwise. When the weight to be carried by the bottom is not con siderable the rams may be constructed racks and operated by pinions driven by an electric motor through suitable reducing gear.

The raising and lowering mechanism may be below a railway track on which the chamber bottom carrying the cylinder and mounted on a truck, may be brought into position beneath the annular chamber, whereupon the rams are raised in order to bring): the cylinder into the chamber. When the heating is complete the rams are again low? ered to rest the bottom on the truck.

In the drawings, Fig. 1 is an elevation of a furnace constructed in accordance with the invention; Fig. 2 is an axial vertical section, and Fig. 3 is a sectional plan on line 3-3 of Fig. 2.

The furnace at is supported on a suitable framework 6. Its annular muffle chamber 0 is surrounded by an annular flue (Z which is in communication with the outside air through radial ports cl controlled by slides d at its upper part it is in communication with a number of radial horizontal flues d which extend across the top of chamber 0.

Adjacent to each flue d is a horizontal flue c which receives fuel gas from a pipe 7 springing from an annular gas main f. At their inner ends each of the pair of flues d and e enters a vertical flue g on the inside wall of the chamber 0, and this flue is connected by a short horizontal flue g at its lower part witha like vertical flue h. This. latter flue enters at its upper part a radial flue h extending over the top of the chamher 0 between two lines (Z3 and terminating at its outer end in avertioal flue 71/2 between the annular flue (Z and tl e outer wall of chamber 0. All the fines 7L2 enter at their lower end an annular collecting flue 7L3 connected with the chimney flue h and each is controlled by a damper 2'.

The chimney draught draws air through ports d into annular flue (Z; here the air is preheated by contact with the Walls of fiues k and passes through flues cl into flues 9 where it meets gas issuing from fiues e. Combustion occurs in flues g and products are drawn by way of lines 9, h, h and h into the collecting flue 7L3. The combustion fines receive attention through holes The ring 7v constituting the movable bottom of the muffle chamber is represented as carrying a cylinder Z to be heated. In Figs. 1 and 2 this ring 7c is shown in full lines in its lowered position and in dotted lines in the position in which it forms the bottom of the mufl'le chamber.

The portion of the ring which extends into the heated Zone of the chamber 0 is of tirebrick and this is carried by an iron ring having a right-angle flange 75 on each periphery to form annular troughs containing sand which receive, in the raised position of the ring, corresponding flanges u'depending from the bottom of the furnace; in this manner the chamber 0 is sealed from air circulation.

The ring is adapted to be carried on a wheeled truck m which can be brought on track rails 17, from a distance to beneath the furnace. The gear here illustrated for lifting the ring from the truck and holding it in position in the chamber 0 comprises four suitably guided rams 0 having rack teeth 0 engaged by the four pinions p mounted on the two shafts g which are driven by bevel gears r and toothed Wheel 1" on a shaft r which are driven from a toothed wheel r from reducing gear .9 itself driven by motor 6.

Having thus described the nature of the said invention and the best means I know of carrying the same into practical effect, I claim 1. An annular muilie furnace comprising an annular muffle chamber,a movable bottom to the said chamber and means for lowering the said bottom and for raising it again into its place in the chamber.

2. An annular mulile furnace for heating a hollow cylinder comprising an annular muffie chamber of mean radius equal to the mean radius of the cylinder, a movable bot tom to the said chamber, means for lowering the said bottom sufficiently to receive the cylinder and means for raising it again into its place in the chamber.

3. An annular mufl'le furnace comprising an annular muffle chamber, a movable ring adapted to close .the bottom of the chamber, rams on which the said ring rest-s and means for lowering and raising the said rams.

4. An annular mufile furnace, a framework carrying the furnace, an annular muffle chamber in the furnace, a ring constituting the bottom of the muiiie chamber, rams on which the said ring rests, a truck adapted to pass between the rams and to carry the ring and means for operating the aims to lower the ring and to deposit it upon the truck.

7 In testimony whereof I have signed my name to this specification.

ARTHUR McDOUGALL DUQKHAM. 

